1. Field of the Invention
The present invention relates to a simultaneous cooling and heating type multiple air conditioner, and, more particularly, to a supercooling apparatus of a simultaneous cooling and heating type multiple air conditioner, which is capable of reducing noise generated from cooling-side heat exchangers during a simultaneous cooling and heating operation and improving cooling capacity of the multi air conditioner.
2. Description of the Related Art
Generally, a simultaneous cooling and heating type air conditioner is a kind of multiple air conditioner. The simultaneous cooling and heating type air conditioner simultaneously performs cooling and heating operations to individually cool or heat rooms where indoor units of the air conditioner are installed.
Specifically, the simultaneous cooling and heating type air conditioner is constructed such that, when one or more rooms are to be heated, the indoor units installed at the corresponding rooms are operated in heating mode, and, at the same time, when one or more rooms are to be cooled, the indoor units installed at the corresponding rooms are operated in cooling mode.
FIG. 1 is a circuit diagram showing a conventional simultaneous cooling and heating type multiple air conditioner operated in main cooling mode.
As shown in FIG. 1, the conventional simultaneous cooling and heating type multiple air conditioner comprises an outdoor unit A, a distributor B, and a plurality of indoor units C.
In the outdoor unit A are mounted compressors 1, outdoor heat exchangers 2, a four-way valve 3, and an accumulator 8.
Between the outdoor unit A and the indoor units C are connected high-pressure pipes 20, 20a, 20b, and 20c, through which high-pressure refrigerant flows, low-pressure pipes 21, 21a, 21b, and 21c, through which low-pressure refrigerant flows, and liquid pipes 22, 22a, 22b, and 22c. The high-pressure pipes 20, 20a, 20b, and 20c, the low-pressure pipes 21, 21a, 21b, and 21c, and the liquid pipes 22, 22a, 22b, 22c extend through the distributor B. On the high-pressure pipes 20a, 20b, and 20c are mounted high-pressure valves 30a, 30b, and 30c, respectively. On the low-pressure pipes 21a, 21b, and 21c are mounted low-pressure valves 31a, 31b, and 31c, respectively.
In the indoor units C are mounted indoor heat exchangers 50a, 50b, and 50c, and electronic expansion valves 55a, 55b, and 55c, respectively.
The conventional simultaneous cooling and heating type multiple air conditioner controls the four-way valve 3, the high-pressure valves 30a, 30b, and 30c, and the low-pressure valves 31a, 31b, and 31c, based on operation mode, such as full cooling mode, main cooling mode, full heating mode, or main heating mode, to simultaneously or individually perform cooling and heating operations.
FIG. 1 shows the main cooling operation of the conventional simultaneous cooling and heating type multiple air conditioner. As shown in FIG. 1, refrigerant discharged from the compressors 1 flows to the liquid pipe 22 through the outdoor heat exchangers 2. At the same time, the refrigerant flows to the high-pressure pipe 20. The refrigerant passing through the outdoor heat exchangers 2 flows through the electronic expansion valves 55a and 55b and the indoor heat exchangers 50a and 50b to cool the rooms where the corresponding indoor units are installed. Subsequently, the refrigerant flows to the compressors 1 through the low-pressure valves 31a and 31b, the low-pressure pipes 21a, 21b, and 21, and the accumulator 8. On the other hand, the refrigerant passing through the high-pressure pipe 20 flows through the high-pressure valve 30c, which is opened, and the indoor heat exchanger 50c to heat the room where the corresponding indoor unit is installed. Subsequently, the refrigerant passing through the indoor heat exchanger 50c joins the refrigerant flowing to the indoor heat exchangers 50a and 50b, and then flows through the indoor heat exchangers 50a and 50b to assist the cooling of the rooms. Thereafter, the refrigerant flows to the compressors 1.
When the conventional simultaneous cooling and heating type multiple air conditioner is operated in the full cooling mode, i.e., when all the indoor units C are operated in the cooling mode, supercooled liquid is supplied from the outdoor heat exchangers 2 to the indoor heat exchangers 50a, 50b, and 50c. Consequently, noise is not generated. When the conventional simultaneous cooling and heating type multiple air conditioner is operated in the main cooling mode, i.e., when at least one of the indoor units C is operated in the heating mode, on the other hand, not only heating-side indoor heat exchanger 50c but also the outdoor heat exchangers 2 servos serve as a condenser.
In this case, supercooling may be insufficient depending on the outdoor temperature surrounding the heating-side indoor heat exchanger 50c, and insufficiently supercooled liquid refrigerant may be introduced into the cooling-side indoor heat exchangers 50a and 50b. 
When the insufficiently supercooled liquid refrigerant is introduced into the cooling-side indoor heat exchangers 50a and 50b, however, severe noise may be generated due to rapid flow speed of the saturated liquid refrigerant. According to circumstances, a large number of bubbles may be generated, and the bubbles prevent smooth flow of the liquid refrigerant. Consequently, the cooling capacity of the conventional simultaneous cooling and heating type multiple air conditioner is lowered.